This program project grant will focus on three main areas. The first will involve therapeutic trails of transfer factor prepared from lymphocytotoxic positive relatives of patients with systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. The second area will deal with long-term clinical and immunopathologic studies of circulating immune complexes in patients with a wide variety of clinical disorders including common infections, connnective tissue disorders, cancer, and various gastrointestinal diseases. The third main area will focus on attempts to define mechanisms possibly related to primary immunodeficiency as well as secondary immune deficiency. Particular emphasis will be directed to studies of suppressor T-cell function and to the effect of circulating humoral factors capable of modulating immune suppression or deficiency.